Furfural is an organic compound with the formula C4H3OCHO. It is a colorless liquid, although commercial samples are often amber. It consists of a formyl group attached to the 2-position of furan. It is a product of the dehydration of sugars, as occur in a variety of agricultural byproducts, including corncobs, oat, wheatbran, and sawdust. The name furfural comes from the Latin word furfur, meaning bran, referring to its usual source. Aside from ethanol, acetic acid and sugar it is one of the oldest renewable chemicals.[5] It is also found in many processed foods and beverages.

Furfural remained a relatively obscure chemical until 1922,[5] when the Quaker Oats Company began mass-producing it from oat hulls.[9] Today, furfural is still produced from agricultural byproducts like sugarcane bagasse and corn cobs. The main countries producing furfural today are the Dominican Republic, South Africa and China.

Furfural dissolves readily in most polar organic solvents, but is only slightly soluble in either water or alkanes.

Furfural participates in the same kinds of reactions as other aldehydes and other aromatic compounds, but has less aromatic character than benzene, as can be seen from the fact that furfural is readily hydrogenated to the corresponding tetrahydrofuran derivatives. When heated in the presence of acids, furfural irreversibly solidifies, acting as a thermosetting polymer.

Between 3% and 10% of the mass of crop residue feedstocks can be recovered as furfural, depending on the type of feedstock. Furfural and water evaporate together from the reaction mixture, and separate upon condensation. The global production capacity is about 800,000 tons as of 2012. China is the biggest supplier of furfural, and accounts for the greater part of global capacity. The other two major commercial producers are Illovo Sugar in the Republic of South Africa and Central Romana in the Dominican Republic [11]

In industrial production, some lignocellulosic residue remains after the removal of the furfural. This residue is dried and burned to provide steam for the operation of the furfural plant. Newer and more energy efficient plants have excess residue, which is or can be used for co-generation of electricity,[14][15] cattle feed, activated carbon, mulch/fertiliser, etc. It also has been used as a glue extender in the North American board industry.[16]

Furfural is an important renewable, non-petroleum based, chemical feedstock. It can be converted into a variety of solvents, polymers, fuels and other useful chemicals by a range of catalytic reductions.[17] Hydrogenation of furfural provides furfuryl alcohol (FA), which is a used to produce furan resin, which are exploited in thermoset polymer matrix composites, cements, adhesives, casting resins and coatings.[18] Further hydrogenation of furfuryl alcohol leads to tetrahydrofurfuryl alcohol (THFA), which is used as a solvent in agricultural formulations and as an adjuvant to help herbicides penetrate the leaf structure. Another important solvent made from furfural is methyltetrahydrofuran. Furfural is used to make other furan derivatives, such as furoic acid, via oxidation,[19] and furan itself via palladium catalyzed vapor phase decarbonylation.[3] Furfural is also a specialized chemical solvent. There is a good market for value added chemicals that can be obtained from furfural [11].

Although it occurs in many foods and flavorants, furfural is toxic with an LD50 of 65 mg/kg (oral, rat).[20] It is a skin irritant and chronic skin exposure can lead to a skin allergy as well as an unusual susceptibility to sunburn.

^ abJohn Stenhouse (1843). "On the Oils Produced by the Action of Sulphuric Acid upon Various Classes of Vegetables. [Abstract]". Abstracts of the Papers Communicated to the Royal Society of London. 5: 939–941. doi:10.1098/rspl.1843.0234. JSTOR111080.

^George Fownes (1845). "An Account of the Artificial Formation of a Vegeto-Alkali". Philosophical Transactions of the Royal Society of London. 135: 253–262. doi:10.1098/rstl.1845.0008. JSTOR108270.